Anastomosis is a procedure where two separate tubular or hollow organs are surgically grafted together to form a continuous fluid channel between them. Vascular anastomosis between blood vessels creates or restores blood flow. When a patient suffers from coronary artery disease (CAD), an occlusion or stenosis in a coronary artery restricts blood flow to the heart muscle. In order to treat CAD, anastomosis is performed between a graft vessel and the affected coronary artery in order to bypass the occlusion and restore adequate blood flow to the heart muscle. This surgical procedure is known as coronary artery bypass grafting (CABG). Anastomosis may be performed in other surgical contexts, such as carotid artery bypass surgery or microvascular surgery.
Conventional anastomosis is performed by suturing two vessels together, which can be time-consuming and painstaking. More recently, magnetic anastomosis devices have been disclosed in U.S. Pat. No. 6,352,543. These devices are magnetic rings, where four rings are used to hold the end of a graft vessel to the side of a target vessel. High-energy magnets are used to enable these rings to hold tissue and maintain an anastomosis. However, high-energy density magnetic materials, such as samarium cobalt (e.g., SmCo5, Sm2Co17, SM3Co4) and neodymium iron boron (e.g., Nd2Fe14B) tend to be brittle, and are prone to chipping or cracking in the manufacturing process. Neodymium iron boron also exhibits poor corrosion resistance. Thus, despite their useful magnetic properties, high-energy density magnetic materials pose challenges in manufacturing, and in ongoing use within a living body. Further, the magnetic rings disclosed in U.S. Pat. No. 6,352,543 place a relatively large amount of metal in direct contact with the bloodstream, increasing the risk of thrombosis, and potentially contributing to restenosis.